1. Field of the Invention
The present invention relates to a rotating electrical machine having a stator core that is composed of a plurality of thin steel plates laminated one over another and integrated with one another, with concave and convex portions formed on the individual thin steel plates being placed into mutual fitting engagement with one another.
2. Description of the Related Art
In the past, there has been known a vehicular alternator having a stator core comprising element iron cores of a hexahedral shape which are deformed to bend or curve, with their adjacent end faces being abutted against each other and bonded to each other, each of the element iron cores being composed of individual thin steel plates laminated and integrated with one another, with concave and convex portions formed on the individual thin steel plates being fitted or engaged with each other (see, for example, a first patent document: Japanese patent application laid-open No. 2002-191142 (FIG. 4)).
In this case, concave and convex portions are formed on each thin steel plate that has a film of a bonding material formed on its surface by means of press working, after which the thin steel plates are laminated one over another to form element iron cores, which are then heated and pressurized under prescribed conditions thereby to deform or shape the thus integrated element iron cores into a cylindrical configuration to provide a stator core.
In the stator core of the above-mentioned vehicular alternator, in order to integrate individual thin steel plates with one another, it is necessary to heat the bonding material applied to the surface of each thin steel plate and to pressurize it in a direction of lamination, so there is a problem of increasing both cost and man-hours.
In addition, with respect to the size or dimension in the direction of lamination of the steel plates, too, it is necessary to grasp the extent of melting of the bonding material, and the management of gaps between adjacent ones of the thin steel plates becomes complicated, thus making it difficult to obtain products of stable quality.
Moreover, there is also a fear of damage or peeling or falling off of the fixed bonding material when the element iron cores are subjected to bending deformation after having been bonded to one another.
On the other hand, it is considered that in order to strengthen the integration of the element iron cores of the stator core in a reliable manner, most portions of the outer peripheral side faces of the element iron cores are welded to one another, such a strategy is not practical in mass-produced goods.